The present invention relates to a method, a system and a device for managing the consumption of electric energy in a domestic environment.
As known, the problem of limiting the total electric power being absorbed in a domestic environment becomes more and more important; this is substantially due to the following two reasons:
first, because it solves the problem of accidental interruptions of electric energy (blackouts), due to the operation of a limiting device (generally a thermal device, sensitive to the current quantity flowing through it), which is associated to the maximum value of the available electric power (contractual power value), as defined in the power supply contract signed between the electricity supplier and the user;
secondly, more in general, because it allows for keeping the electric power absorption below a determined level, so avoiding the so-called absorption xe2x80x9cpeaksxe2x80x9d and favoring significant economies upstream, by virtue of a better planning of the electric energy production.
The first reason concerns above all those countries which, due to their not being self-sufficient from an electric energy production standpoint, tend to impose limitations on the domestic consumptions, to the benefit of the industrial and manufacturing consumptions; this is for instance the situation in Italy, where the typical domestic electric energy supply contract covers 3 kW only.
On the other hand, the above cited second reason has a more general application, since it also concerns those countries which, even if plenty of electric energy (e.g. by virtue of nuclear power plants), have anyway to gradually limit the consumption, in observance of international directions for the environmental protection, which impose limit values to harmful emissions.
To this purpose, incentive procedures being founded on instruments for the reduction of the cost of the electric energy, are presently studied, for instance in Europe, which provides for the application of differential tariffs according to the following two criterions:
a first criterion, of the xe2x80x9chorizontalxe2x80x9d type, being already adopted in many countries, which consists in applying differentiated tariffs for time intervals, in particular lower tariffs during the night hours;
a second criterion, of the xe2x80x9cverticalxe2x80x9d type, presently still under study, which consist in applying, for the same time interval, tariffs being differentiated in function of the level of electric power absorption, according to the procedures adopted for instance by the Internal Revenue Office for income taxation.
For the above purposes, a number of solutions have been proposed, concerning the rationalization of the energy consumption in the domestic environment.
In most known solutions, the management of the electric energy consumption in a household environment is realized by means of a central supervision unit; this unit manages the various electric loads, through a direct control of the electric household apparatuses equipped with suitable control systems, or using xe2x80x9csmartxe2x80x9d sockets, which control the supply of electric energy to the apparatuses themselves, through ON-OFF operations.
The central supervision units of the above type are featured by the fact that they carry out an activity of the automatic type, even if following an appropriate initial configuration by the individual using the appliance (hereinafter referred to as xe2x80x9cconsumerxe2x80x9d); the central supervision units are also characterized in that they are arranged at a hierarchical level being higher with respect to the electric household users, i.e. performing a master role, with active control on the latter.
However, such known xe2x80x9ccentralizedxe2x80x9d supervision or managing systems have some drawbacks.
A first type of drawback is due to the complex of the supervision unit, which should be a programmable one, since it has to manage a plurality of household appliances at different times and with different procedures; now, this necessarily presumes a relevant programming engagement for the consumer.
A second type of drawback is the poor efficiency of the supervision unit, normally limiting itself to manage the electric supply of the various household apparatuses, based on a mere ON/OFF activity alone, and which under an excessive power absorption condition, provides for the deactivation of the power user having a minor importance priority. In order to clarify the concept of xe2x80x9cpoor efficiencyxe2x80x9d expressed in this second point, let us consider for instance the event where the deactivated power user is a washing machine performing its water heating step. In this event, in fact, the total cutoff of the machine will hinder the exploitation of the thermal energy already accumulated by the water, whereas it would be possible to exploit it should the washing machine continue the drum rotation, with just about. 0,1 kW power, even by interrupting the water heating, which is typically associated to a power absorption of 2 kW.
A third type of drawback is related to the cost of the supervision unit, which requires, for allowing its programming, an appropriate consumer-interface, usually consisting of a keyboard and a display, and an electronic control system with adequate processing power and memory (such as a Personal Computer).
A fully alternative solution to this xe2x80x9ccentralizedxe2x80x9d control and supervision approach for the household users is disclosed in the European Patent Application EP-A-0 727 668, in the name of the applicant of the present invention, which is based on a system architecture of the distributed type.
Such a document describes a set of household appliances capable of constantly receiving information concerning the total absorption of power of all the household users (household appliances, lighting installation, room conditioning system, etc.), the maximum available power (power supply contract), the current time (clock function) and the likely different cost of the energy depending on the time ranges.
Such information are supplied by means of a proper meter, located outside the household appliances, which may be the same electricity meter, suitable prearranged, or a specific ad hoc optional device; the means used for transmitting the information may be of any type, but the preferred one is the power line, i.e. the same electric network. Based on the information received from the external meter, and depending upon determined priority levels associated to the various household appliances, the same household appliances (which are individually fitted with an appropriate electronic control system and suitable interface means to the electric network) are able to xe2x80x9cspontaneouslyxe2x80x9d and automatically limit their own electric power consumption, so as to maintain the total consumption of the whole household environment constantly below the limit imposed by the value of the contractual power, the above requiring neither any external centralized supervision system, nor any intervention by the consumer.
Thus, the system described in EP-A-0 727 668 allows for achieving important advantages, in terms of simplicity of use and flexibility, with respect to the previous known solutions based on the application of a central supervision unit.
The system described in EP-A-0 727 668 provides for the control system of each individual household apparatus ta receive the information concerning the instantaneous total consumption of the electric energy, which is transmitted by the external meter at regular time intervals on the communication bus, the latter consisting, as said, of the same electric network.
However, such an approach of transmitting the information which relates to the instantaneous total consumption of the electric energy at regular time intervals may cause some drawbacks.
In particular, EP-A-0 727 668 suggests adopting a relatively long fixed interval between two subsequent transmissions of the above said information, i.e. in the order of several tens of seconds; as a result, the household appliances may not be able to react promptly enough, in order to avoid exceeding the maximum power absorption allowed.
Let us assume, for instance, that a household appliance is activated, which therefore draws electric energy from the mains, in the following situation:
a) immediately after the external meter has sent on the communication network the information relating to the instantaneous total consumption; and
b) when the level of absorbed power being determined by the operation of other apparatuses is already close to the maximum limit value.
It is obvious, in this situation, that the further current consumption caused by the new household apparatus just activated will determine the exceeding of the contractual or usable power value, with a consequent possible blackout; this because in the time interval required for sending the new consumption information by the external meter, the other household apparatuses of the network cannot react and automatically limit their own consumption of electric power for m the total consumption of the whole domestic environment below the limit imported by the value of the contractual power.
Theoretically, the above drawback could be reduced by increasing the transmission frequency of the above information, for example with transmission intervals in the order of a second; however, it is clear that such a solution would considerably increase the communications flow on the bus, due to nearly constant presence of the information relating to the instantaneous total consumption on the network.
It is the object of the present invention to solve the above drawback and indicate a solution for the improved managing of the consumption of electric energy in a domestic environment, in order to avoid the exceeding of the limit of maximum power which can be supplied, as provided by the electric energy supply contract, or another convenient limit appropriately established by the consumer.
Within this general frame, the present invention has the aim of indicating a managing method, of the type as described in EP-A-0 727 668, where, however, the communication network among the various household apparatuses can be smartly engaged, so avoiding useless overloading, save if strictly required, and warranting as a consequence, a greater solidity of the same communication system.
Further aims of the present invention are to provide a managing procedure and a metering device for the realization of the above system, in a simple and efficient way.
These and other aims, which will be better highlighted in the following, are obtained according to the present invention through a method, a system and a device for managing the consumption of electric energy in a domestic environment incorporating the features of the annexed claims, which form an integral part of the present description.